05−98

DIAGNOSTICS− SFI SYSTEM (2AZ−FE) 052N9−38 DTC P0101 MASS OR VOLUME AIR FLOW CIRCUIT RANGE/PERFORMANCE PROBLEM

CIRCUIT DESCRIPTION Refer to DTC P0100 on page 05−91. DTC No. DTC Detection Conditions Trouble Areas SHigh voltage: Conditions (a), (b) and (c) continue for more than 10 seconds (2 trip detection logic): (a) Engine speed less than 2,000 rpm (b) Engine temperature 70_C (158_F) or higher (c) Voltage output of Mass Air Flow (MAF) meter more than 2.2 P0101 V (varies with Throttle Position [TP] sensor voltage) SMAF meter SLow voltage: Conditions (a) and (b) continue for more than 10 seconds (2 trip detection logic): (a) Engine speed more than 300 rpm (b) Voltage output of MAF meter less than 0.65 V (varies with TP sensor voltage) MONITOR DESCRIPTION The MAF meter is a sensor that measures the amount of air flowing through the throttle valve. The ECM uses this information to determine the injection time and to provide an appropriate air−fuel ratio. Inside the MAF meter, there is a heated platinum wire which is exposed to the flow of intake air. By applying a specific electrical current to the wire, the ECM heats it to a specific temperature. The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to these components of the MAF meter. The voltage level is proportional to the through the sensor, and the ECM uses it to calculate the intake air volume. If there is a defect in the sensor, or an open or short in the circuit, the voltage level deviates from the normal operating range. The ECM interprets this deviation as a malfunction in the MAF meter and sets the DTC. Example: If the voltage is more than 2.2 V, or less than 0.65 V while idling, the ECM determines that there is a malfunc- tion in the MAF meter and sets the DTC. MONITOR STRATEGY

Related DTCs P0101: Mass air flow meter rationality Required Sensors/Components (Main) Mass air flow meter Crankshaft position sensor, engine coolant temperature sensor and throttle position Required Sensors/Components (Related) sensor Frequency of Operation Continuous Duration 10 seconds MIL Operation 2 driving cycles Sequence of Operation None

2005 SCION tC REPAIR MANUAL (RM1104U) 05−99 DIAGNOSTICS− SFI SYSTEM (2AZ−FE) TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present See page 05−19 Mass Air Flow Meter Rationality (High Voltage): Engine speed Less than 2,000 rpm Engine coolant temperature 70°C (158°F) or more Mass air flow meter voltage 4.9 V or less Mass Air Flow Meter Rationality (Low Voltage): Engine speed More than 300 rpm Mass air flow meter voltage 0.2 V or more Fuel cut OFF TYPICAL MALFUNCTION THRESHOLDS Mass Air Flow Meter Rationality (High Voltage): Mass air flow meter voltage More than 2.2 V (varies with throttle position sensor voltage) Mass Air Flow Meter Rationality (Low Voltage): Mass air flow meter voltage Less than 0.65 V (varies with throttle position sensor voltage) WIRING DIAGRAM Refer to DTC P0100 on page 05−91. INSPECTION PROCEDURE HINT: Read freeze frame data using a hand−held tester or OBD II scan tool. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air−fuel ratio was lean or rich, and other data, from the time the malfunction occurred. 1 CHECK ANY OTHER DTCS OUTPUT(IN ADDITION TO DTC P0101)

(a) Connect a hand−held tester or OBD II scan tool to the DLC3. (b) Turn the ignition switch to ON. (c) Turn the tester or scan tool ON. (d) On the tester, select the following menu items: DIAGNOSIS / ENHANCED OBD II / DATA INFO / COR- RENT CODES. (e) Read DTCs. (f) If using an OBD II scan tool, refer to the instruction manual. Result : Display (DTC Output) Proceed To P0101 and other DTCs A P0101 B HINT: If any DTCs other than P0101 are output, troubleshoot those DTCs first. B REPLACE MASS AIR FLOW METER

A

GO TO DTC CHART (See page 05−54)

2005 SCION tC REPAIR MANUAL (RM1104U)